1. Technical Field
The present invention relates to an improved apparatus and system for improving the quality of fluids untreated from petroleum and gas well drilling and recovery operations, mining operations, and during other industrial activities, and specifically to a method that does not simply involve the use of traditional filtration or separation methods. The present system separates contaminants from a variety of fluids utilizing a pressure separation apparatus which can also create and facilitate hydrodynamic cavitation conditions within the fluid. This results in the improved separation and removal of particulates and dissolved constituents from the fluid.
2. Description of Related Art
The safe and effective removal of contaminants from fluids is a consistent problem faced by many industries. The impurities accumulated by fluids during the hydrologic cycle, industrial processes and manufacturing activities may appear in both suspended and dissolved forms. Suspended solids may be generally be classified as particles larger than molecular size (i.e. particle sizes greater than 10−3 mm), which are supported by buoyant and viscous forces existing within the fluid. Dissolved materials (i.e. particle sizes less than 10−3 mm) consist of molecules and ions, which are held by the molecular structure of fluid.
The presence of suspended and/or dissolved solids in waste fluid and other fluids is undesirable for several reasons. The presence of visible suspended solids may be aesthetically displeasing. Likewise, the presence of suspended and/or dissolved solids allows for the adsorption of other chemicals or biological matter into the fluid. Due to the standards promulgated by government agencies, excessive contaminants must be removed from potable fluid, waste fluid and other types of contaminated fluid streams before the effluent may be discharged to the environment or recycled for reuse. If established discharge-contamination levels are exceeded, governmental authorities and agencies may impose surcharges and penalties on the entity responsible for the discharge of fluids which do not meet or exceed the appropriate standard of quality.
For example, both terrestrial and offshore oil and gas fields produce large quantities of contaminated fluid that can have significant environmental effects if they are not handled, remediated and discharged properly. In a typical petroleum formation, formation fluid lies adjacent the formation layer containing the desired hydrocarbons (e.g. oil and natural gas). As a result, when these hydrocarbons are removed from the formation via the wellbore, formation fluid is brought to the surface along with the hydrocarbons. Drilling fluids are utilized to assist in oil and gas well drilling operations. If required and in order to achieve maximum recovery, recovery fluids will be injected into the formation to provide additional motive force to recover the hydrocarbons from the formation. As a result, increasing volumes of both formation fluid and injected fluid are produced and remain untreated in the recovery of oil and gas from the formation. The treatment of untreated fluid is a major component of the cost of producing oil and gas.
Untreated fluid characteristics and physical properties vary considerably depending upon the geographic location of the field, the geological formation with which the untreated fluid has been in contact for thousands for years, and the type of hydrocarbon product being recovered. The contaminants of untreated fluid may include salt content expressed as salinity, conductivity, or total dissolved solids (“TDS”). Other contaminants may include slurries having dispersed oil droplets, dissolved organic compounds including dissolved oil, drilling fluids, polymers, well treatment and workover chemicals, and other organic and inorganic compounds that can lead to toxicity. Some of these are naturally occurring in the untreated fluid while others are related to chemicals that have been added for drilling and well-control purposes. Further, contaminants can also include dissolved gases including hydrogen sulfide and carbon dioxide, bacteria and other living organisms, and dispersed solid particles. Untreated fluids also typically exhibit low concentrations of dissolved oxygen and non-volatile dissolved organic materials. Because of the contaminants in untreated fluid, it requires no large amount of thought to surmise that the direct release or reinjection of untreated fluid into the ocean, upon land, or into the subsurface formation would have damaging effects on the environment and pose health risks to animals and humans in both the short and long term.
One prior art solution for treating untreated fluid involves pumping the fluid through disposable filters to filter and remove the suspended solids. There are several problems with this prior art solution. First, once the disposable filters have been used they are typically considered hazardous waste and they must be sent to special disposal facilities for disposal after use further depleting the increasingly diminishing landfill space available. Second, the disposable filters are themselves relatively costly and therefore do not provide an economical treatment solution. Third, the constant changing of used disposable filters with clean or new disposable filters is labor intensive. Fourth, the disposable filters have a relatively short lifespan as they (1) are constructed of paper-based material which is easily degraded by contaminants, (2) are unable to continually support the sheer mass of the contaminants that are loaded onto the filters during filtration operations, and (3) cannot withstand typical backwash cleaning pressures. Consequently, a need exists for a way to minimize or eliminate the need for disposable filters in the removal of suspended solids from waste streams such as untreated fluid.
Another problem encountered in removing contaminants from fluids is the expense and difficulty in designing a system that can remove contaminants that vary widely in chemical and physical make-up. As alluded to above, the chemical make-up of contaminants ranges widely from dissolved oil and brine to bacteria in untreated fluids. Similarly the physical make-up of the contaminants varies in particle size from the ionic range (brine) to the micro and macro particle range (oil droplets, sand particles). Such a wide range of contaminants presents several challenges in treating untreated fluids. For example, slurries and biological contaminants can plug filtration equipment, and separation of metals from contaminated fluid typically requires expensive chemical precipitation processes. These are just a sampling of the difficulties encountered in the treatment of industrial waste fluid which illustrate the complexity and expense of treatment facilities that must be constructed to treat such waste fluid in lieu of disposable filters. Because such treatment facilities are complex, they are typically not mobile, therefore requiring industrial waste fluid be stored on-site and then shipped to a treatment facility. Consequently, a need exists for an improved method and apparatus for treating contaminated fluid. In one aspect, the apparatus and method should be mobile and able to be economically installed near the location where the untreated contaminated fluid originates. In another aspect, the apparatus and method should provide sufficient treatment to meet regulatory standards required to permit discharge of fluid directly into the environment and/or for reuse in industrial settings. Further, the method and apparatus should be able to provide for the treated fluid needs of the facility where the apparatus is located. As such, a need exists in the art for a portable, highly efficient filtration apparatus and method which can separate suspended and dissolved solids and other contaminants in a variety of environments. Further, a need exists for an improved apparatus and method of removing particles from fluids in either a liquid or gaseous state. Further, a need exists for an apparatus and method which can consistently remove particles of a desired size so as to efficiently and consistently reduce the chance of the imposition of a surcharge for violating quality control standards and the release of untreated effluents.